In the field of drug discovery screening, influence of a drug administered to a sample of cells or the like is evaluated by measuring light emitted from the cells in certain cases. Patent Literature 1 discloses a measurement device that monitors a biological response of cells to electric-field stimulation by fluorescence detection. This measurement device employs a configuration in which an electrode pair of a coaxial cable shape or a parallel flat plate shape including a positive electrode and a negative electrode can be located in each of wells in which the cells are placed. Patent Literature 2 discloses a measurement device that treats a membrane potential of a cell through the use of electrical stimulation. This measurement device includes an electrode pair of two parallel electrodes for generating an electric field in an observation area of a well.